Firelighter Fluid

ABSTRACT

A barbecue firelighter fluid comprises biodiesel and a biodiesel soluble natural emulsifying agent as a fuel. Natural emulsifiers include acacia, gelatine, cholesterol and lecithin. The fluid has an increased burn time compared with conventional fluids based on hydrocarbons, for example.

This invention relates to firelighter fluids of the type which may be used to initiate combustion of wood-based fuel especially for barbecues, irrespective of whether the fuel is in the form of charcoal (lump wood or briquettes) or natural wood for use in outdoor wood fires.

Barbecue fuel lighting fluids are already known and are supplied either as a liquid or as a gel. In use, they are designed to be applied to the barbecue fuel and allowed to be at least partially absorbed before being lit. However, they are typically based on kerosene, alcohol, paraffin, white spirit or other solvents, which are environmentally disadvantageous, and their availability could encourage users to employ paraffin or even petrol as a substitute, with extremely dangerous potential consequences. Currently available products are in any event potentially dangerous in use, because they have a flashpoint as low as 10 -18° C. in the case of alcohol-based fluids and 60 -75° C. in the case of petroleum-based fluids. They also have a fast burn time and a tendency to drip or pool, both of which can result in difficulty in ignition of the barbecue fuel especially when in the form of briquettes, in that the fluid may become expended before the fuel has attained self-sustaining ignition. Users are thus tempted to add more fluid to already-hot fuel, with resulting risk of dangerous flare.

It is an object of the present invention to provide an alternative firelighter fluid which possesses the following attributes:

-   -   (a) is more environmentally acceptable     -   (b) is safer in use and storage     -   (c) provides enhanced performance, particularly in burn time,         than such fluids as are currently available.

In one aspect, the present invention provides a firelighter fluid comprising biodiesel and a biodiesel soluble natural emulsifying agent as the fuel. Natural emulsifiers are numerous and include acacia, gelatine, cholesterol and lecithin.

Both constituents of firelighter fluids according to the invention are more environmentally acceptable than ingredients of petroleum- or hydrocarbon-based fluids. The emulsifying agent has an effect of retarding the combustion properties of the fluid and, thus, increasing the burn time.

In an embodiment of the present invention, the soluble agent is conveniently provided by lecithin, a natural product comprising a complex mixture of glycolipids, triglycerides and phospholipids, for example phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol. Lecithin is present in a number of natural products but is for the greater part obtained by solvent extraction from soy beans, when it is referred to as soya lecithin. Lecithin may also be obtained to a lesser degree from oilseed rape, sunflower, rice and eggs.

Optionally, for use in the present invention, lecithin may be modified by fractionation by mixing with an alcohol, typically ethanol, to selectively dissolve the alcohol-soluble phospholipids, separating the alcoholic solution from the insoluble residue and removing the alcohol by evaporation to yield a fraction rich in phosphatidylcholine.

Biodiesel is an alternative to petroleum-based diesel fuel and is becoming commercially available, as are fuels derived from a biomass-to-liquid process, using for example the Fischer Tropsch reaction. Biodiesel is manufactured from vegetable oils, including used cooking oil, by a transesterification process to form glycerol and esters from the triglyceride starting material; the ester component is separated from the glycerol and constitutes the biodiesel. Oilseed rape yields a vegetable oil which is particularly useful for production of biodiesel fuel. However, alternatives to oilseed rape include palm oil and soy bean oil. In the present specification, fuels derived from a biomass-to-liquid process are to be included within the definition of biodiesel.

For use in the present invention, the natural emulsifying agent may be used at a concentration in the range 0.1 to 75% by weight of the total fuel, preferably 5 to 35% by weight.

It has been found that lighting fluids according to the invention have a flashpoint in the range 120 -140° C. and are thus inherently safer to use than most currently available fluids. When ignited, they burn steadily without flaring, sudden deflagration, spitting, dripping or explosion and show considerable enhancement of burning times and burn rates. It has also been found that the resulting flare produced if the fluid is applied directly on to hot coals is much reduced and the inventive fluid is thus inherently less dangerous that other currently available liquids.

In an example of the invention, a biodiesel fuel obtained from EcoOla Biofuels of Galway, Republic of Ireland, was blended with 20% by weight of soya lecithin. The resulting thickened fuel was used as a lighting fluid for a barbecue in which the fuel was briquette charcoal, known to be more difficult and slower to light than lumpwood varieties. The lighting fluid was applied according to the method outlined below. The charcoal was satisfactorily ignited to a condition suitable for grill cooking to commence after 20-30 minutes. These lighting times are comparable with currently available liquids and charcoals.

In another aspect of the invention, therefore, a method of igniting charcoal for a barbecue comprises providing cellulose-containing kindling in a barbecue container, applying a firelighter fluid having a flashpoint of 120° C. or above to the kindling and allowing the kindling to absorb the fluid, applying barbecue fuel to the kindling and igniting the kindling.

The cellulose-containing kindling may comprise newspaper which is preferably folded and twisted to form a semi-rigid stick, a plurality of such sticks, say up to ten, being arranged in the container to form a criss-crossed array around and through which air can circulate.

In an example, four or five such kindling sticks are provided, to which a suitable amount of the fluid is added and allowed to soak. The soakage greatly reduces dripping and pooling observed when unthickened fluids are typically applied direct to charcoal. The charcoal is then placed on the sticks in a pyramidal shape leaving the stick ends protruding for lighting purposes.

According to the present invention, independent analysis of burning time of the fluid shows considerable unaided enhancement of burning time when compared to other leading liquid types currently available.

TABLE 1 Liquid Type Avg. Burn Time Avg. Burn Rate Naphtha, petroleum 1.54 minutes. 46.2 seconds/gm. hydrotreated, light. ¹ Soya derived 2.34 minutes. 70.2 seconds/gm. Biodiesel-Unthickened. OSR ² derived 2.79 minutes. 83.7 seconds/gm. Biodiesel-Unthickened. OSR derived Biodiesel/ 4.06 minutes. 121.8 seconds/gm.  20 wt % Soya Lecithin. ³ ¹ The industry standard liquid. ² Oilseed Rape. ³ Fluid according to the present invention.

Due to the higher flashpoint of biodiesel based liquids and the resulting difficulty in ignition, and also for comparison purposes, an ad hoc test method was developed that gave reliable ignition and ongoing combustion of the samples and this method was adopted for all the above liquids tested.

The method consisted of burning a firelighter sample in a shallow dish which contained a fine metal mesh supporting a piece of absorbent paper onto which the sample of firelighter was placed. The paper acted as a wicking material, while the fine mesh elevated the paper very slightly above the dish base allowing the flame to spread and burn all the sample and wick to its maximum. The dish and its contents were supported on a normal laboratory tripod and gauze with one side of the gauze elevated by 10 mm. The paper used in the tests was cut to the size of the dish and incorporated a ‘tag’ which was used as the ignition point in the tests, this part of the paper being positioned at the elevated part of the dish. This arrangement provided reliable lighting and consistent burning of the firelighter samples. Identically sized and shaped papers of the same mass were used in each test, and a firelighter sample of 2 gms used. In all cases the fluids ignited readily with no one fluid showing faster/slower ignition time, than any other.

The example of the present invention as provided in Table 1 burns 2.6 times longer than hydrotreated light petroleum naphtha [the industry standard lighting fluid for BBQs] and 1.5 times longer than Oilseed Rape derived unthickened liquid the enhanced burn time and burn rate providing the user with significantly enhanced reliability in lighting performance without compromising the time between ignition and readiness for cooking. 

1. A firelighter fluid comprising biodiesel and a biodiesel soluble natural emulsifying agent as the fuel.
 2. A firelighter fluid according to claim 1, in which the natural emulsifying agent comprises acacia, gelatin, cholesterol and/or lecithin.
 3. A firelighter fluid according to claim 2, in which lecithin is the emulsifying agent and is modified by fractionation to yield a fraction rich in phosphatidylcholine.
 4. A firelighter fluid according to claim 1, in which the biodiesel is formed from vegetable oils derived from oilseed rape, palm oil and soy bean oil, or is formed from a biomass-to-liquid process.
 5. A firelighter fluid according to claim 4, in which the vegetable oil comprises oilseed rape.
 6. A firelighter fluid according to claim 1, in which the natural emulsifying agent is used at a concentration in the range 0.1 to 75% by weight of the total fuel.
 7. A firelighter fluid according to claim 6, in which the concentration of the emulsifying agent is from 5 to 35% by weight of the total fuel.
 8. A method of igniting charcoal for a barbecue, the method comprising providing cellulose-containing kindling in a barbecue container, applying a firelighter fluid having a flashpoint of 120° C. or above to the kindling and allowing the kindling to absorb the fluid, applying barbecue fuel to the kindling and igniting the kindling.
 9. A method according to claim 8, in which the firelighter fluid comprises a biodiesel and a biodiesel soluble natural emulsifying agent as the fuel.
 10. A method according to claim 8, in which the cellulose-containing kindling comprises newspaper.
 11. A method according to claim 10, in which the newspaper is folded and twisted to form semi-rigid sticks, a plurality of such sticks being arranged in the container to form a criss-crossed array around and through which air can circulate. 